config.md,image-layout.md: s/should/SHOULD/ for appropriate terms

Signed-off-by: Erik Hollensbe <[email protected]>

Author: Erik Hollensbe

config.md

@@ -112,7 +112,7 @@ Note: Any OPTIONAL field MAY also be set to null, which is equivalent to being a
 
 - **config** *object*, OPTIONAL
 
-  The execution parameters which should be used as a base when running a container using the image.
+  The execution parameters which SHOULD be used as a base when running a container using the image.
   This field can be `null`, in which case any execution parameters should be specified at creation of the container.
 
    - **User** *string*, OPTIONAL
@@ -144,11 +144,11 @@ Note: Any OPTIONAL field MAY also be set to null, which is equivalent to being a
 
      Default arguments to the entrypoint of the container.
      These values act as defaults and are replaced with any specified when creating a container.
-     If an `Entrypoint` value is not specified, then the first entry of the `Cmd` array should be interpreted as the executable to run.
+     If an `Entrypoint` value is not specified, then the first entry of the `Cmd` array SHOULD be interpreted as the executable to run.
 
    - **Volumes** *object*, OPTIONAL
 
-     A set of directories which should be created as data volumes in a container running this image.
+     A set of directories which SHOULD be created as data volumes in a container running this image.
      If a file or folder exists within the image with the same path as a data volume, that file or folder is replaced with the data volume and is never merged.
      **NOTE:** This JSON structure value is unusual because it is a direct JSON serialization of the Go type `map[string]struct{}` and is represented in JSON as an object mapping its keys to an empty object.
 

image-layout.md

@@ -15,7 +15,7 @@ The image layout is as follows:
 
 - `blobs` directory
     - Contains content-addressable blobs
-    - A blob has no schema and should be considered opaque
+    - A blob has no schema and SHOULD be considered opaque
     - Directory MUST exist and MAY be empty
     - See [blobs](#blobs) section
 - `oci-layout` file